Marine Microbiology Flashcards
Describe some of the main characteristics of prokaryotes.
- Include bacteria and archaea
- Occur in large numbers
- Relatively small cells with small genome
- Large diversity
- Most phyla poorly understood.
What are the three main methodologies to obtain microbial genomes?
- Single-cell genomics
- Culture
- Metagenomics.
What are polyextremophiles and give an example.
Adapted to live in habitats where various physicochemical parameters reach extreme values e.g. microbes.
Name the different types of polyextremophiles.
- Hyperthermophiles (temperatures)
- Acidophiles (pH)
- Halophiles (salinity)
- Piezophile/barophile (pressure).
Define oligotrophy.
Growth at low nutrient concentrations.
Why are marine microbes so small?
Small cell size is a way to cope with low substrate
availability. It increases the surface area to volume ratio – very important in marine systems!• Substrate uptake is via cell
membrane proteins. Increasing
SA/Vol improves the ability to
supply nutrients to the
cytoplasmic volume.
What controls and limits the population size of marine microbes?
Nutrient availability.
Describe the growth rate of marine microbes and why they are that way.
Low growth rate as nutrients are removed rapidly.
How do different microbes get their energy?
- Phototrophs (photosynthetic, energy from sunlight)
- Chemotrophs (energy from oxidation of chemicals).
What are the different types of chemotrophs?
- Chemo-litho-trophs - energy from oxidation of inorganic chemicals
- Chemo-organo-trophs - energy from oxidation of organic chemicals.
How do microbes obtain their carbon?
- Autotrophic - An organism that can make organic molecules from inorganic nutrients
- Heterotrophic - An organism that cannot make organic molecules from inorganic nutrients. Depends on organic matter for energy generation and precursors for cell material.
Give an example of a photoautotroph.
Cyanobacteria.
Give an example of a chemoautotroph.
Thaumarchaeota.
Give an example of a photoheterotroph.
Halobacteria.
Give an example of a chemoheterotroph.
Proteobacteria.
What are the typical characteristics of the marine environment?
- pH 8.1
- High salt concentrations
- Often low nitrogen and phosphorous concentrations
- Often low oxygen concentrations
- Often low concentrations of organic carbon.
What are phytoplankton?
Oxygenic photoautotrophs in photic (surface) water.
Name the most abundant primary producers in the oceans.
- Cyanobacteria
- Diatoms
- Dinoflagellates.
What is marine snow and why is it important?
- Detritus which has aggregated into larger particles
- the major transport of primary production energy into deeper oceanic layers.
What is detritus made of and how?
Mucopolysaccharides or extra polymeric substances (EPS) are produced by
bacteria, algae, phytoplankton, zooplankton etc.
At what depth is the deep sea zone?
> 1000m.
How does nutrient status vary between inshore and open ocean?
- Higher nutrients inshore
- Due to higher productivity from more phototrophic organisms
- Bays and estuaries exposed to urban and agricultural pollution.
From what does microbial metabolic diversity arise?
Ability to generate energy from different sources.
What represents the largest portion of biomass and activity in the ocean?
Bacteria.
